The cortical networks that support working memory and visual attention will be investigated in the proposed set of fMRI experiments, with an emphasis on the role of early visual cortex. Subjects will perform psychophysical discrimination and detection tasks while their brain activity is imaged in a 3T scanner. The experiments will shed light on questions concerning the nature of visual working memory, such as whether it is ever iconic rather than symbolic. They will also clarify the mechanisms underlying sustained attention, contributing to the discussion in the literature as to whether attention acts by boosting the signal coming from relevant neuronal channels. Our preliminary results reveal a striking dissociation between working memory and visual attention, which we explore in terms of underlying computational mechanisms. Many experimentalists and theorists posit that problems maintaining information underlies the core symptomology in a range of neurological disorders. A better understanding of the basic neural mechanisms underlying visual attention and working memory will lead to improved diagnostic, prognostic, and therapeutic procedures for these disorders. [unreadable] [unreadable] [unreadable]